Method of making cushioned gears or the like



T. L. FAWICK METHOD OF MAKING CUSHIONED GEARS OR THE LIKE Sept. 27, 1949.

2 Sheecs-Sheet 1 Filed April 27, 1945 INVENTOR THO/M146 L. FflW/CK ATTORNEY Sept. 27, 1949. T. L. FAWICK METHOD OF MAKING CUSHIONED'GEARS OR THE LIKE Filed April 27, 1945 2 Sheets-Sheet 2 2% SW NW MN N hm NroR. lffiw/ax BY s I Arm/aver Patented Sept. 27, 1949 UNITED STATES PATENT OFFICE METHOD MAKING CUSHIONED GEARS OR THE LIKE Thomas L.,Fawick, Akron, Ohio Application April 2'7, 1945, Serial No. 590,692

This invention relates to cushioned gears and the like andto procedure for making the same.

Its chief objects are to provide an improved gear having cushioning means interposed between its toothed. portion and its hub or the portion that isadaptedto be engaged with a mounting for the gear; to provide accuracy in the cutting of the gear teeth in spite of such eccentricity as may result from the interpositioning of the cushioning means before the teeth are cut; to provide a gear comprising natural rubber as the cushioning means with improved provision for protecting the rubber from contact with oil; and to provide advantageous procedure for providing a gear having someor all of those advantages.

Other objects are to provide a cushioned gear assembly having a pitch diameter not much greater than the diameter of a shaft which is a part of the assembly, and to provide such a gear with provision for transmission of heavy torque.

Of the accompanying drawings:

Fig. 1 isan axial section, with the shaft or hub in elevation, of a gear embodying and made in accordance with my invention in its preferred form.

' Fig. 2 is a similar view of the shaft or hub member and cushioning means thereon as they appear atone stage of the process.

Fig. 3 is an axial section of another embodiment of the invention, with provision for transmission of heavy torque.

Referring to the embodiment illustrated in Figs. 1 and 2 of the drawings, a shaft l first has mold vulcanized upon and adhered to it a set of spaced. apart, deformable rings, the end rings, l I, H, being of oil-resistant synthetic material such as chlor-butadiene, polymerized vinyl chloride-or co-polymers of vinyl chloride and vinyl acetate, and the intermediate rings, l2, [2, being. of a composition comprising natural rubber, of about the characteristics of tire-tread rubber, for its long-lasting cushioning effect.

The shaft with the deformable rings thereonis then forced lengthwise, in a procedure well known in the art, into-a metal'sleeve or gear-blank l3 which ultimately becomes the toothed portion of the gear, and the dimensions are such that this operation deforms the rings so that they substantially fill the space between the shaft and the gear-blank, their shape and relation then being as shown in Fig. 1.

The gear blank l3 preferably is preformed with a cylindrical counterbore M in each end and, after the assembly of the gear-blank with the 4 Claims. (Cl. 29- 159.2)

shaft and its cushioning rings, which may result in some eccentricity of the blank in relation to the shaft, the cylindrical wall of each counterbore is lightly cut or ground, as by mounting the shaft in a lathe, and rotating the gear blank by rotating the shaft, while so operating upon the wall of the counterbore, to make the wall truly concentric with the shaft when the cushions are substantially free from extraneous. forces acting between the sleeve and the shaft,v and to make it of proper diameter to receive the accurately sized end portion of a. spacing collar l5 having upon it an outwardly projecting. stud [6 adapted to fit into an open-end: slot IT formed in the end margin of the gear blank,.and provided with a pair of set-screws l8, [8 for securing it upon the shaft.

The gear blank thus being held firmly in such relationship to the shaft as is determined by the balance of the. forces in the deformed cushioning rings, the set of gear teeth, l9, l9, are formed upon it, while it is soheld, the gear blank being held or driven by holding or driving of the shaft.

Then the spacing collars I5- are removed from the assembly, and, if desired, the annular end margins of the gear-blank, to the depth of the countersink, can be cut off, at the lines X--X, and discarded.

The resulting assembly is such that the set of teeth are concentric .with the shaft when the cushioning members are in a condition of balanced stresses, and the cushioning action of the gear has its start from that condition.

This protective arrangement is more broadly described and claimed in my U. S. Patent No. 2,428,932.

. In the embodiment shown in Fig. 3, the shaft, ma, is of waisted form in the region of the resilient rings, Ma and l2a, but the procedure for assembling the shaft and its resilient rings with the gear blank, 13a, and holding the latter in positionwhile-the gear teeth, I ea, areeut in concentric relation to the shaft, is substantially the same as that described with reference to Figs. 1 and-2, but while the gear blank is so held it is formed also, at each end, with a set of splines 20', '21}, each set being adapted to receive a set of complemented internal splines formed in a driving ring 2|;

Each of the driving rings 24 is formed with a circumferentially spaced set of threaded holes for the threaded stems of a set of studs 22, 22 each having secured by vulcanized adhesion on its relatively large cylindrical head a cushioning ring or bushing 23 of rubber-like material which is held under radial compression by a surrounding metal bushing 24, the three members 22, 23 and 24 being assembled as above described with reference to the members 10, H, l2 and [3 of Figs. 1 and 2.

The outer surface of each of the metal bushings 24 can be lightly cut or ground, after assembly with the cushion 23 and stud 22, by mounting the stud in a lathe, to make the outer surface of the metal bushing concentric with the stud, and of accurate size, with the cushion in a condition of substantially balanced stress. This procedure is mentioned also in my copending application Serial No. 587,892, now Patent No. 2,460,636, and in my copending application Ser. No. 686,013, which is a division of the present application.

The metal bushings 24 of each set occupy, preferably with a fairly tight fit, respective cylindrical holes in a torque-transmitting member 25 secured upon the shaft 16a by a key 26, the members 25 preferably being slid into position, on the bushings 24, after the stud assemblies 22, 23, 24 have been screwed into the members 21.

The gear assembly shown in Fig. 3 is adapted to sustain heavier torque than that shown in Fig. 1, by reason of the fact that the cushions 23 of Fig. 3 sustain the torque in compression instead of only in shear, and because they are at a relatively large radius from the axis of rotation. As they cushion the torque with relatively high resistance and consequently without great deformation, the cushioning rings Ha, 12a in Fig. 3 serve chiefly for centering the teeth [9a, and for insulating against transmission of vibration or sound, as they and the rubber bushings 23 completely insulate the gear teeth from the shaft.

The invention provides the advantages that are set out in the above statement of objects and modifications are possible without sacrifice of all of those advantages and without departure from the scope of the appended claims.

I claim:

1. The methodof making a cushioned rotary assembly which comprises interposing under radial stress in an annular space between radially facing surfaces of inner and outer rigid members, so that it insulates them from each other, cushioning material having substantially the resilient deformability of vulcanized soft-rubber, allowing said rigid members to assume a relationship determined by the said radial stress of the said material, then temporarily securing the two rigid members in the relative positions that they thus assume under the force of the deformable material alone and performing a shaping operation upon one of the rigid members while sustaining the shaping force by engagement with the other rigid member.

2. The method of making a cushioned rotary assembly which comprises interposing under radial stress in an annular space between radially facing surfaces of inner and outer rigid members, so that it insulates them from each other, cushioning material having substantially the resilient deformability of vulcanized soft-rubber, allowing said rigid members to assume a relationship determined by the said radial stress of the said material, then temporarily securing the two rigid members in the relative positions that they thus assume under the force of the deformable material alone and performing a shaping operation upon one of the rigid members while sustaining the shaping force by engagement with the other rigid member, the said securing being effected by temporarily interposing a spacer material between the two rigid members.

3. The method of making a cushioned rotary assembly which comprises interposing under radial stress in an annular space between radially facing surfaces of inner and outer rigid members,

, so that it insulates them from each other, cushioning material having substantially the resilient deformability of vulcanized soft-rubber, allowing said rigid members to assume a relationship determined by the said radial stress of the said material, then temporarily securing the two rigid members in the relative positions that they thus assume under the force of the deformable material alone and performing a shaping operation upon one of the rigid members while sustaining the shaping force by engagement with the other rigid member, the said securing being effected by shaping one of the rigid members, after its assembly with the other recited elements, to receive a pre-formed spacer member between it and the other rigid member, and so mounting the spacer member, the spacer member being removed after the first-mentioned shaping operation.

4. The method of making a cushioned rotary assembly which comprises interposing under radial stress in an annular space between radially facing surfaces of inner and outer rigid members, so that it insulates them from each other, cushioning material having substantially the resilient deformability of vulcanized soft-rubber, one of said rigid members being formed with a removable anchorage portion, allowing said rigid members to assume a relationship determined by the said radial stress of the said material, holding the rigid members, by engagement with said portion, in the relative positions that they thus assume under the force of the deformable material, per- I forming a shaping operation upon one of the rigid members while sustaining the shaping force by engagement with the other rigid member, and thereafter removing said anchorage portion from the rigid member.

THOMAS L. FAWICK.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,165,933 Alquist Dec. 28, 1915 1,508,387 7 Findlater Sept. 16, 1924 1,948,473 Marshall Feb. 20, 1934 12,086,720 Malquist July 13, 1937 2,167,705 Batten Aug. 1, 1939 2,182,803 Gee Dec. 12, 1939 2,182,942 Gee Dec. 12, 1939 2,397,626 Shriver Apr. 2, 1946 FOREIGN PATENTS Number Country Date 171,295 Great Britain Nov. 17, 1921 

